Escapement mechanism



June 16, 1942.

J. F. KocA ESCAPEMEN-T. MECHANISM Filed May 1, 1940 ly M ,da

Patented June 16, 1942 @NET " gilet? ES smear stock Typewriter Company,

corporation of illinois Application May 1, 19410, Serial No. 332,789

(Cl. 19t- 88) 4 Claims.

This invention relates in general to means for cushioning elements to avert shock and particularly to a typewriter escapement mechanism.

The primary object of the present invention is the provision of new and improved means for .cushioning the shock of a movable element of a typewriter escapement mechanism before the said element reaches a iXed stop abutment so as to overcome shock, reduce vibrations and noises, and prevent the clashing of parts.

Another object of the invention is the provision of an operating part of a typewriter escapement mechanism having attached thereto flexible means to permit unrestrained movement of the Said part, and a resilient element having considerably less flexibility and resiliency than the flexible means co-operating with the operatingpart so as to absorb and cushion the shock and blow of the operating part prior to the time the said part impacts with a xed stop, the resilient element permitting unrestrained movement and operation of the flexible means.

A further object of the invention is to provide an escapement mechanism having a pivotally movable element arranged adjacent a fixedstop and urged in a predetermined direction by a ilexible element fastened to a pin on the pivoted element and to a pin on a iixed member, there being a resilient member also connected to the pins in a manner to permit undisturbed operation of the flexible element but absorbing and cushioning the shock or blow of the pivoted element prior to the time the pivoted member reaches the iixed stop.

Numerous other objects and advantages will be apparent throughout the progress of the following speciiication.

The accompanying drawing illustrates a selected embodiment of the invention and the views therein are as follows:

Fig. 1 is a rear elevation of escapement mechanism applied to the rear side of a typewriter, and embodying the invention,the parts being shown in normal rest position;

Fig. 2 is a view similar to Fig. l but showing the position which certain of the parts attain during operation;

Fig. 3 is a detail sectional view on the line 3-3 of Fig. 2; and

Fig. 4 is a detail perspective view of the resilient cushioning member.

The particular mechanism herein disclosed to illustrate the invention is shownapplied to the popular, well known Woodstock typewriter although the invention is susceptible for applica-1.55

Woodstock, Ill., a

tion to other makes of typewriters. The said typewriter herein illustrated in part comprises a frame 2 which is provided with rails upon which a carriage (not shown) is free to slide transversely.

A rack li having limited pivotal movement, and spring urged in a predetermined normal operating position, is mounted on the carriage at the rear of the machine and moves transversely with the carriage. rlhe carriage with its attached rack l is drawn toward the right, Figure 1, by suitable resilient means, such as by a tape, fastened to a part oi the carriage and to a spring urged revolubly mounted member mounted on the typewriter frame. The resilient means tends normally to draw the carriage and rack in the direction of the arrows, Figures 1 and 2. The

stresses tending to displace the carriage are resisted by the engagement of the rack l with a pinion G, which is rigidly held from movement in a clockwise direction, as viewed in Figures l and 2*,by a pawl 3 pivoted at it to an escapement lwheel I2. The pawl is normally maintained in engagement with the pinion 5 by means of a spring I4 secured to the escapement wheel i2. The pawl 8 is arranged so as freely to permit movement of the pinion Ei in av counter-clockwise direction, as viewed in Figures l and 2, so that the carriage may be readily returned in the usual `manner against the aforementioned resilient means. A

The escapement wheel l2 is provided with a plurality of outwardly extending teeth liequal in number to the teeth I8 on the pinion 6. In actual practice it has been found that sixteen teeth on the escapement wheel and pinion are very satisfactory for the proper performance of the machine. The escapement wheel is mounted on a pivot pin 20 for rotation thereabout. The central portion of this ratchet wheel extends transversely a considerable distance from the plane of the web portion 22, Figure 3, to form a bearing sleeve 24. The pinion 5 in turn is mounted rotatively upon this cylindrical bearing sleeve 2li, as clearly shown in Figure 3. The parts are maintained in assembled relationship by the machine screw 2S which threadedly engages the pivot pin axially thereof. The pivot pin 20 is provided with an axially extending cylindrical shank portion 2S for xedly positioning it, together with the ratchet wheel and pinion, to the machine frame. The machine frame is provided with a bore 3@ to receive and support the cylindrical shank of the pivot pin.

The remainder of the escapement mechanism 'mostly is of well known construction and includes a bracket member 32 which is supported at 34 and 36 between pivot bearings 38 and 40 threadedly mounted in opposed rigid projections 42 and 44 on the machine frame. A space link operated by the spacing bar may be operatively connected to a part 46 on the bracket 32 to tilt the bracket 32 from front to rear, so as -to disengage a movable stop dog 48 from a tooth I6 on the escapement wheel. Immediately upon movement of the dog 48 from a tooth I6, the resilient means will pull the carriage until the freed tooth I6 engages the fixed dog 53. Upon release of the spacing bar, lthe 4bracket 32 will return to its normal position whereby the tooth I6 will be freed from the ixed dog 50 and the next succeeding tooth I6 will be at rest against the movable dog 48. The tilting or pivotal movement of bracket 32 is also accomplished by the depression of a key, the key having an operative connection with a frame 52 pivoted on lpins 54, and having a part engageable with the bracket 32 to tilt the bracket and permit the escapement which is referred to above.

The dog 48 is pivoted at 56 to the bracket 32, and comprises one arm of a bell-crank 58 which is engageable with the teeth -I6 on the escapement wheel I2. The other arm Y6I) Vof the bell-crank 58 has a spring 62 fastened thereto, tending to urge the bell-crank toward a fixed stop pin 64. The bell-crank 58 has a striking face or stop abutment 66 adapted for engagement with a stop pin 68. The bell-crank 58 has its upper arm positioned between the stop pins 64 and 68 whereby the lateral `movement of dog 48 is limited.

The fixed dog 5!! is fastened to the bracket Y32 by a fastening member 1D, the stem of which passes through a slot I2 in the bracket 32 to permit adjustment of the xed dog 50.

The striking of the teeth I6 on the escapement wheel I2 -against the dog 48 shifts the dog 48 on its pivot to the left, Figures 1 and 2, `causing -the face 66 to strike against the stop pin `6B, tending to set up a vibration as well as a clashing sound or noise each time a key or -the space bar is released after being first depressed. To overcome these disadvantages, resilient means is provided to retard the movement of the dog 48 just prior to the time the striking face 66 hits against the stop pin 68. This resilient means comprises a member 14, Figure 4, made of resilient, though relatively stiff wire. The member 14 terminates in upper and lower eyes or loops 'I6 and 18, respectively, Yconnected by a bowed integral Aportion 8B. The eye 'I6 fits around the fixed pin-6 while the eye 'I8 lits about the pin on vthe arm 6I) of the bell-crank. The eve 'I8 is of sufficient size to permit limited movement or some lost'I play of Y the pin so that the springl 62 operates the bellcrank within proper limits and unrestrained by the lmember "I4, The member 'I4 performs no function until 'the striking face 66 comes `almost to engagement with the pin-68 at which time the e strain is transmitted `to the member 14. The strain so transmitted is taken up `by the member 'I4 Acausing the movement or lblow to be cushioned. Therefore, instead of the face 66 hitting the stop pin 68 a direct blow, a cushion is Vinter-r stop, cushioning the blow and absorbing the Y shock. The bowing of the member I4 provides resiliency and softens the blow of the bell-crank when it reaches a predetermined position. As the bell-crank almost reaches the end of the travel the stress is transmitted to the bowed member 14 tending to pull it, or straighten it, but inasmuch as this member 14 is relatively stiff it will spring back to its normal position after the strain has been released and the movement of the bell-crank in a counter-clockwise direction, as viewed in Figures 1 and 2, has ceased.

The invention therefore provides a simple, inexpensive, shock-absorbing cushioning device in the form 'of a bowed link which connects a movable member and a fixed member to reduce and absorb shocks and vibrations, allowing the parts to come to restsilently and preventing the clashing of parts.

Changes may be made in the form, construction and arrangement of the parts without departing from the spirit of the invention or sacrificing any of its advantages and the right is hereby reserved to make all such changes as fairly fall Vwithin the scope 'of the following claims.

The invention is hereby claimed as follows:

l. Escapement mechanism comprising an escapement dog adapted for limited pivotal movement, a relatively iixed 'stop ,for engagement by said dog, a pin on the dog, and a bowed spring member having one end secured to said fixed stop and the other end thereof terminating in an eye into which the pin isreceived and retained, said eye being larger than the pin to permit a predetermined .amount `of movement of the pin in the eye before engagement therewith when the dog is moved toward and before engagement with said xed stop, 'continued movement of the dog creating a :pull on the bowed member to provide a resilient retarding effect on the dog before .the dog engages `said stop.

2. Escapement mechanism comprising. an escapement dog in the form Vof a bell-crank adaptedfor limited pivotal movement, a pin on the dog, a vrelatively iiat bowed spring member having its ends terminating in eyes, a fixed pin receivable in one of said eyes, afpin on the bellcrank Vand receivable in the other eye, said latter eye being larger than its 'cooperating pin to permit a predetermined amount of free movement of the pin in .the eye before engagement therewith, engagement of the pin with the eye by the 4movement of the bell-crank effecting a force tending to expand the bowed member and slowingfurther movement of the dog resiliently, and spring means for returning the dog to a predetermined position.

3. Escapement .mechanismA comprising a movable member, a` bracket to whchthe movable member is movably mounted, -means to cushion the movable member just prior to the end of its movement in a predetermined direction, said means comprising a Aone pieceresilient bowed member having its ends terminatingin loops, a pin on the bracket and receivable in one loop,

,. a pin on the movable member receivable in the other loop, said latter pin being smaller than the latter loop to permit .unrestrained movement of the movable member to `a predetermined position, and a contraction spring having its ends attached to said pins to urge normally thefmovable member in a predetermineddirection.

4. Escapement mechanism comprising an escapement dog adapted .for limited pivotal movement, a relatively 4iixed stop for engagement by said dog upon movement of said dog in one direction, a pin carried by said dog, and a bowed spring member having loop means at one end connected to said fixed stop and loop means at the other end thereof connected to said pin carried by the dog, said bowed spring member and loop means being arranged to first permit substantially free movement of said dog towards said fixed stop without flexing the bow spring and then to cause stressing of the bowed spring mem-'ber within its elastic limits by further movement of said dog toward said xed stop whereby resilently to retard the movement of said dog toward said fixed stop prior to engagement of the dog and fixed stop thereby to reduce the force with which the dog otherwise would strike the fixed stop.

JAMES F. KOCA. 

